Introduction to Computers-Lesson2 an overview

An introduction to computer system

1. Kafui A. Prebbie [email protected]
24
An Overview of the
Computer System

2. Kafui A. Prebbie [email protected]
25
The Parts of a Computer System •What is a Computer?
•Hardware
•Software
•Data
•Users

3. Kafui A. Prebbie [email protected]
26
•A computer is an electronic device used to process
data.
•A computer can convert data into information that is
useful to people.
•A complete computer system includes four distinct
parts:

Hardware; Software; Data; User
The Parts of a Computer System
- What is a Computer?

4. Kafui A. Prebbie [email protected]
27

5. Kafui A. Prebbie [email protected]
28
•A computer's hardware consists of
electronic devices; the parts you
can see and touch.
•The term "device" refers to any
piece of hardware used by the
computer, such as a keyboard,
monitor, modem, mouse, etc.
The Parts of a Computer System
- Hardware

6. Kafui A. Prebbie [email protected]
29
Computer Hardware
Processing
Internal
Memory
Output
Input
•
Keyboard
•
Mouse
•
Monitor
•
Printer
Secondary
Storage

7. Kafui A. Prebbie [email protected]
30
•Input devices accept data and instructions from
the user or from another computer system. The
keyboard and mouse are examples of input
devices.
•Output devices return processed data back to the
user or to another computer system. The printer
and monitor are examples.
•Communications devices (such as modems and
network interface cards) perform both input and
output, allowing computers to share information.
Looking Inside the Machine –
Input and Output Devices

8. Kafui A. Prebbie [email protected]
31

9. Kafui A. Prebbie [email protected]
32

10. Kafui A. Prebbie [email protected]
33
•Storage devices hold data not currently being used
by the CPU. Data is commonly stored on a magnetic
or optical disk. Each type uses a special medium for
storing data on its surface.
•A disk drive is a device that reads data from and
writes data to a disk. Most new computers feature a
floppy disk drive, a hard disk drive, and an optical
disk drive.
•The most common optical storage devices are CD-
ROM and DVD-ROM drives.
Looking Inside the Machine
- Storage Devices

11. Kafui A. Prebbie [email protected]
34

12. Kafui A. Prebbie [email protected]
35
•Software – also called programs – consists
of organized sets of instructions for
controlling the computer.
•Some programs exist for the computer's
use, to help it manage its own tasks and
devices.
•Other programs exist for the user, and
enable the computer to perform tasks for
you, such as creating documents.
The Parts of a Computer System
- Software

13. Kafui A. Prebbie [email protected]
36
•Data consists of raw facts, which the
computer can manipulate and process into
information that is useful to people.
•Computerized data is digital, meaning that
it has been reduced to digits, or numbers.
The computer stores and reads all data as
numbers.
•Although computers use data in digital
form, they convert data into forms that
people can understand, such as text,
numerals, sounds, and images.
The Parts of a Computer System - Data

14. Kafui A. Prebbie [email protected]
37
Ten different
symbols in
the decimal
system
Numbers above 9
use more than 1 digit

15. Kafui A. Prebbie [email protected]
38
•People are the computer's operators, or
users.
•Some types of computers can operate
without much intervention from people,
but personal computers are designed
specifically for use by people.
The Parts of a Computer System – Users

16. Kafui A. Prebbie [email protected]
39
Looking Inside the Machine •
Types of Hardware
• The CPU
• Memory
• How Memory is Measured
• Input and Output Devices
• Storage Devices

17. Kafui A. Prebbie [email protected]
40
A computer's hardware devices are categorized as
follows: •Processor
•Memory
•Input and output (I/O) devices
•Storage devices
Looking Inside the Machine –
Types of Hardware

18. Kafui A. Prebbie [email protected]
41
01101111

19. Kafui A. Prebbie [email protected]
42
Looking Inside the Machine - The CPU
The procedure that transforms raw data into useful
information is called processing. This function is
divided between the computer's processor and
memory.

20. Kafui A. Prebbie [email protected]
43
•The processor is also called the central processing
unit (CPU). It manages all devices and performs
the actual processing of data.
The CPU consists of one or more chips attached to
the computer's main circuit board (the
motherboard).
Looking Inside the Machine - The CPU

21. Kafui A. Prebbie [email protected]
44
Central Processing Unit

CONTROL
UNIT
ARITHMETIC

LOGIC
UNIT

INTERNAL
MEMORY
INPUT
OUTPUT
SECONDARY
STORAGE
FLOW OF DATA

FLOW OF INSTRUCTIONS

FLOW OF CONTROL
S
L
OW

SLOW

F A S T
SLOW

slow

22. Kafui A. Prebbie [email protected]
45
Central Processing Unit (CPU) •
The Central Processing Unit is the brain of the computer
•
It is made up of the Control Unit (directs all
operations), The Arithmetic-Logic Unit (carries out
actual manipulations), and the Internal Memory
•
All three parts are stored on an electronic device called
microchip or simply the chip. •
Elements of the chip are transistors connected together
in circuits called Integrated Circuits. •
Registers are high speed memory devices located in the
ALU to hold data

23. Kafui A. Prebbie [email protected]
46
Internal Memory •
Also known as Main memory.
•
List of instructions to be executed (programs) and
data are stored here. •
Two primary types of internal memory are The
Random Access Memory (RAM) and The Read
Only Memories (ROM).
•
Data is stored in binary representations with
permanent series of electronic switches, and
miniature transistors called “flip-flops”.

24. Kafui A. Prebbie [email protected]
47
Read Only Memory (ROM) •
Read Only Memory is Non Volatile or permanent.
•
User cannot store information on the ROM.
•
Rom contains the Bootstrap information that the
computer needs to start after the system disk is
inserted.
•
Some computers (Macintosh) have instructions for
graphics and mouse stored on the ROM. •
Instructions of the ROM are referred to as
Firmware. •
Information is stored by permanent switches

25. Kafui A. Prebbie [email protected]
48
Random Access Memory (RAM) •
Random Access Memory is Volatile (not
permanent, items in RAM are lost when computer
s turned off).
•
User uses RAM to store information.
•
Information is stored ion RAM by non permanent
transistors called “flip-flops”. •
Storage locations are identified by their address
(in binary). •
RAM of a computer is discussed in terms of
Kilobytes and megabytes
.

26. Kafui A. Prebbie [email protected]
49
RAM (Address Locations)
•
Storage locations are referenced
by address. •
Memory is measured by bytes
•
1024 bytes = 1 Kb (kilobyte)
•
1024 Kbytes = 1 Mb (megabyte)
•
1024 Mb = 1 Gb (gigabyte)

0001

0010

0011

0100

0101

0110

0001 0010 0011 0100 0101
01010011
Address
Memory

27. Kafui A. Prebbie [email protected]
50
•Memory also consists of chips attached to the
motherboard.
•Memory holds data and program instructions
as the CPU works with them. This memory is
called Random Access Memory (RAM).
•The CPU can find any piece of data
in RAM, when it needs it for processing.
•RAM is volatile, meaning it holds data
only when the power is on. When the power
is off, RAM's contents are lost.
Looking Inside the Machine - Memory

28. Kafui A. Prebbie [email protected]
51
Other Types of Memory •
PROM – Programmable ROM. This kind allows the
user to program initial instructions (“burn in” the
chips special instructions).
•
EPROM – Erasable Programmable Read Only
Memory. •
Bubble Memory is used in RAM to avoid volatility.
•
Use of Batteries to power RAM in case of power
failures

29. Kafui A. Prebbie [email protected]
52
Internal Representation of Data and
Instructions
•
Computers use the Binary Number System (base 2) to
represent data (characters and digits).
Decimal
Binary
Decimal
Binary
006110
117111
21081000
31191001
4100101010
5101

30. Kafui A. Prebbie [email protected]
53
Bits and Bytes

The smallest usable unit of measure for memory is
the byte – the amount of memory required to hold
one character, like the letter A or the numeral 2.
•
Basic Unit of Measure in a computer is the Bit
(contraction of Binary and Digit). •
A Bit represents a switch and can be in one of two
states, on or off. •
A group of 8 Bits is called a Byte.
•
Computers combines bytes to represent large numbers
(and symbols). •
Number of bits used by a computer depends on the
type of computer.

31. Kafui A. Prebbie [email protected]
54
Bits and Bytes (Symbols) •
Computers use a pattern of bits to represent symbols.
•
EBCDIC (Extended Binary Coded Decimal
Interchange Code) was developed by IBM and uses
8 bits to represent data
•
ASCII (American Standard Code for International
Interchange) also uses 8 bits for data representation.
This has become a standard for personal computers.

32. Kafui A. Prebbie [email protected]
55
Computers work with larger chunks of data,
measured in multiple bytes, as shown below:
UnitApprox. Value Actual Value
(bytes) (bytes)
Kilobyte (KB)1,000 1,024
Megabyte (MB)1,000,000 1,048,576
Gigabyte (GB)1,000,000,000 1,073,741,824
Terabyte (TB)1,000,000,000,000 1,099,511,627,776
Looking Inside the Machine
– How Memory is Measured

33. Kafui A. Prebbie [email protected]
56
Secondary Storage •
Secondary storage is memory outside the CPU
and Internal memory. •
Secondary storage is needed because of limited
amount of memory and volatility of RAM. •
Secondary storage comes either as disk or tape

34. Kafui A. Prebbie [email protected]
57
Software: Bringing the Machine to Life
•What is Software?
•System Software
•Application Software

35. Kafui A. Prebbie [email protected]
58
•Software is a set of electronic instructions that
tells the computer how to do certain tasks. A
set of instructions is often called a program.
•When a computer is using a particular
program, it is said to be running or executing
the program.
•The two most common types of programs are
system software and application software.
Bringing the Machine to Life –
What is Software?

36. Kafui A. Prebbie [email protected]
59

37. Kafui A. Prebbie [email protected]
60
•System software exists primarily for the computer
itself, to help

the computer perform specific
functions.
•One major type of system software is the operating
system (OS). All computers require an operating
system.
•The OS tells the computer how to interact with the
user and its own devices.

•Common operating systems include Windows, the
Macintosh OS, OS/2, and UNIX .
Bringing the Machine to Life –
System Software

38. Kafui A. Prebbie [email protected]
61
•Application software tells the computer how to
accomplish tasks the user requires, such as
creating a document or editing a graphic
image.
•Some important kinds of application software
are:
Word processing programsSpreadsheet software
Database managementPresentation programs
Graphics programsNetworking software
Web design tools and browsersInternet applications
Communications programs Utilities
Entertainment and education Multimedia authoring
Bringing the Machine to Life - Applications

39. Kafui A. Prebbie [email protected]
62
•List the four parts of a computer system.
•Identify four types of computer hardware.
•List five units of measure for computer memory and
storage.
•Provide two examples of input and output devices.
•Name and describe three types of storage devices.
•Differentiate the two main categories of computer
software.
•List four specific types of application software.